<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#float1, #float2 {
 width: 100px;
 height: 20px;
 background-color: green;
 margin-left: auto;
}
#spacer {
 height: 30px;
}
</style>
</head>
<body>
<div id="container">
 <div id="float1"></div>
 <div id="spacer"></div>
 <div id="float2"></div>
</div>
</body>
</html>
